[DOC] New Datetime format rfc3339_lenient

[CaptainDredge]

What do you want to do?

• Request a change to existing documentation
• Add new documentation
• Report a technical problem with the documentation
• Other

Tell us about your request. Provide a summary of the request and all versions that are affected.
We need to add new format rfc3339_lenient format introduced in #11465 in the datetime formats doc here

Format name: rfc3339_lenient
Description: An RFC3339 compatible datetime formatter which is much faster than other full date lenient formats like strict_date_optional_time
Pattern and examples:

Year:
        YYYY (eg 1997)
Year and month:
        YYYY-MM (eg 1997-07)
 Complete date:
        YYYY-MM-DD (eg 1997-07-16)
 Complete date plus hours and minutes:
        YYYY-MM-DDThh:mmTZD (eg 1997-07-16T19:20+01:00)
 Complete date plus hours, minutes and seconds:
        YYYY-MM-DDThh:mm:ssTZD (eg 1997-07-16T19:20:30+01:00)
 Complete date plus hours, minutes, seconds and a decimal fraction of a second
        YYYY-MM-DDThh:mm:ss.sTZD (eg 1997-07-16T19:20:30.45+01:00)
        YYYY-MM-DDThh:mm:ss,sTZD (eg 1997-07-16T19:20:30,45+01:00)

What other resources are available? Provide links to related issues, POCs, steps for testing, etc.
Backport 2.x: opensearch-project/OpenSearch#12107

[CaptainDredge]

cc: @hdhalter

[hdhalter]

Thanks, @CaptainDredge ! Can you please create the documentation PR with this information?

[bbarani]

@CaptainDredge Can you please confirm if this feature will make it to 2.12.0 release? If so, can you create the documentation PR with this information?

[CaptainDredge]

@bbarani yes this has already been merged in 2.x so it should make it to 2.12.0. I've raised documentation PR here
#6337